Showing papers on "Porites compressa published in 2014"

Vibrio coralliilyticus Strain OCN008 Is an Etiological Agent of Acute Montipora White Syndrome

Abstract: Identification of a pathogen is a critical first step in the epidemiology and subsequent management of a disease. A limited number of pathogens have been identified for diseases contributing to the global decline of coral populations. Here we describe Vibrio coralliilyticus strain OCN008, which induces acute Montipora white syndrome (aMWS), a tissue loss disease responsible for substantial mortality of the coral Montipora capitata in Kāne'ohe Bay, Hawai'i. OCN008 was grown in pure culture, recreated signs of disease in experimentally infected corals, and could be recovered after infection. In addition, strains similar to OCN008 were isolated from diseased coral from the field but not from healthy M. capitata. OCN008 repeatedly induced the loss of healthy M. capitata tissue from fragments under laboratory conditions with a minimum infectious dose of between 10(7) and 10(8) CFU/ml of water. In contrast, Porites compressa was not infected by OCN008, indicating the host specificity of the pathogen. A decrease in water temperature from 27 to 23°C affected the time to disease onset, but the risk of infection was not significantly reduced. Temperature-dependent bleaching, which has been observed with the V. coralliilyticus type strain BAA-450, was not observed during infection with OCN008. A comparison of the OCN008 genome to the genomes of pathogenic V. coralliilyticus strains BAA-450 and P1 revealed similar virulence-associated genes and quorum-sensing systems. Despite this genetic similarity, infections of M. capitata by OCN008 do not follow the paradigm for V. coralliilyticus infections established by the type strain.

Application of 1H-NMR metabolomic profiling for reef-building corals.

Abstract: In light of global reef decline new methods to accurately, cheaply, and quickly evaluate coral metabolic states are needed to assess reef health. Metabolomic profiling can describe the response of individuals to disturbance (i.e., shifts in environmental conditions) across biological models and is a powerful approach for characterizing and comparing coral metabolism. For the first time, we assess the utility of a proton-nuclear magnetic resonance spectroscopy (1H-NMR)-based metabolomics approach in characterizing coral metabolite profiles by 1) investigating technical, intra-, and inter-sample variation, 2) evaluating the ability to recover targeted metabolite spikes, and 3) assessing the potential for this method to differentiate among coral species. Our results indicate 1H-NMR profiling of Porites compressa corals is highly reproducible and exhibits low levels of variability within and among colonies. The spiking experiments validate the sensitivity of our methods and showcase the capacity of orthogonal partial least squares discriminate analysis (OPLS-DA) to distinguish between profiles spiked with varying metabolite concentrations (0 mM, 0.1 mM, and 10 mM). Finally, 1H-NMR metabolomics coupled with OPLS-DA, revealed species-specific patterns in metabolite profiles among four reef-building corals (Pocillopora damicornis, Porites lobata, Montipora aequituberculata, and Seriatopora hystrix). Collectively, these data indicate that 1H-NMR metabolomic techniques can profile reef-building coral metabolomes and have the potential to provide an integrated picture of the coral phenotype in response to environmental change.

Coscinaraea marshae corals that have survived prolonged bleaching exhibit signs of increased heterotrophic feeding

Abstract: Colonies of Coscinaraea marshae corals from Rottnest Island, Western Australia have survived for more than 11 months in various bleached states following a severe heating event in the austral summer of 2011. These colonies are situated in a high-latitude, mesophotic environment, which has made their long-term survival of particular interest as such environments typically suffer from minimal thermal pressures. We have investigated corals that remain unbleached, moderately bleached, or severely bleached to better understand potential survival mechanisms utilised in response to thermal stress. Specifically, Symbiodinium (algal symbiont) density and genotype, chlorophyll-a concentrations, and δ13C and δ15N levels were compared between colonies in the three bleaching categories. Severely bleached colonies housed significantly fewer Symbiodinium cells (p < 0.05) and significantly reduced chlorophyll-a concentrations (p < 0.05), compared with unbleached colonies. Novel Symbiodinium clade associations were observed for this coral in both severely and moderately bleached colonies, with clade C and a mixed clade population detected. In unbleached colonies, only clade B was observed. Levels of δ15N indicate that severely bleached colonies are utilising heterotrophic feeding mechanisms to aid survival whilst bleached. Collectively, these results suggest that these C. marshae colonies can survive with low symbiont and chlorophyll densities, in response to prolonged thermal stress and extended bleaching, and increase heterotrophic feeding levels sufficiently to meet energy demands, thus enabling some colonies to survive and recover over long time frames. This is significant as it suggests that corals in mesophotic and high-latitude environments may possess considerable plasticity and an ability to tolerate and adapt to large environmental fluctuations, thereby improving their chances of survival as climate change impacts coral ecosystems worldwide.

Response of reef corals on a fringing reef flat to elevated suspended-sediment concentrations: Molokaʻi, Hawaiʻi

Abstract: A long-term (10 month exposure) experiment on effects of suspended sediment on the mortality, growth, and recruitment of the reef corals Montipora capitata and Porites compressa was conducted on the shallow reef flat off south Moloka'i, Hawai'i. Corals were grown on wire platforms with attached coral recruitment tiles along a suspended solid concentration (SSC) gradient that ranged from 37 mg l(-1) (inshore) to 3 mg l(-1) (offshore). Natural coral reef development on the reef flat is limited to areas with SSCs less than 10 mg l(-1) as previously suggested in the scientific literature. However, the experimental corals held at much higher levels of turbidity showed surprisingly good survivorship and growth. High SSCs encountered on the reef flat reduced coral recruitment by one to three orders of magnitude compared to other sites throughout Hawai'i. There was a significant correlation between the biomass of macroalgae attached to the wire growth platforms at the end of the experiment and percentage of the corals showing mortality. We conclude that lack of suitable hard substrate, macroalgal competition, and blockage of recruitment on available substratum are major factors accounting for the low natural coral coverage in areas of high turbidity. The direct impact of high turbidity on growth and mortality is of lesser importance.

Quantification of virus-like particles suggests viral infection in corals affected by Porites tissue loss

Abstract: Porites tissue loss is a common disease of Porites compressa on Hawaiian reefs. Despite its prevalence, to date, the aetiological agent of the disease has not been found. The apparent lack of a microbial causative agent in the similar disease Porites bleaching with tissue loss, as well as increasing evidence of viral infections in scleractinian corals and Symbiodinium, led us to hypothesise that a virus may be responsible. Electron microscopy revealed the presence of numerous and varied virus-like particles (VLPs) in healthy and diseased P. compressa colonies. While overall virus numbers were similar in all samples, the abundance of a group of icosahedral VLPs differed significantly between healthy and diseased colonies. While not conclusive, these results suggest that viruses may play a role in this disease, and provide a basis for further studies.

Screening for antibacterial, antifungal and cytotoxic agents in three hard coral species from Persian Gulf

Abstract: Within the frame of a biodiversity and bioactivity study of marine macro organisms from the Persian Gulf, three hard coral species extracts were investigated for cytotoxic, antibacterial and antifungal activities against five human pathogenic microorganisms. All concentrations of extracts from three hard corals showed no antifungal activity towards the tested strains. In antibacterial assays the hard coral extracts showed significant activity solely against Staphylococcus aureus with MICs ranging from 3 to 9 μg/mL. The highest antibacterial activity was found in the aqueous methanol extract of Porites compressa with an inhibition zone of 22 mm against Staphylococcus aureus at 18 μg/mL extract concentration. It is important for future research to concentrate on finding the mechanisms employed by corals to defend themselves against invasion, the mechanism of infections and the type of chemical compounds in coral extracts that inhibit antibacterial growth or proliferation in underexplored areas such as the Persian Gulf.